Datasheet

Page 57 of 161
nRF8001 Product Specification
Revision 1.2
Information exchange can be divided into four typical scenarios as illustrated in Figure 24. on page 56
1. System command – System event
The application controller sends a system command and receives acknowledgment from
nRF8001 in the form of an event.
2. System event
nRF8001 sends an event to the application controller triggered by a predefined condition.
3. Data command – Data event
The application controller sends a data command requesting application data transfer or
reception. Data is returned in the form of a Data event if the transaction is successful.
4. Data event
nRF8001 sends an event packet to the application controller. This is triggered by a data
packet transfer by the peer device or a predefined condition related to application data
transfer.
18.1 Packet structure
ACI information traffic is organized in packets. Each packet consists of a 2 byte header field followed by a
variable length packet payload.
The byte ordering follows the Little Endian format (Least significant byte transmitted first). In this part of the
document capitalized letters as in MSB (Most Significant Byte) indicate bytes.
Text data is transmitted leftmost character first.
For information on bit ordering and description of the ACI physical transport, see Part A, section 7.1 on
page 21
Figure 25. illustrates the ACI packet.
Figure 25. ACI packet structure
The packet header consists of two bytes. The first byte represents the total packet length of the packet
(excluding the length field) in bytes. The opcode field contains the unique OP code for the specific
command/event.
The PDU length is determined by the ACI packet type. Some ACI packets may have a variable length PDU
(Protocol Data Unit) depending on the parameter options for the specific ACI packet.
OP code
PDU (length depends on Command/Event type)
Length
LSB
MSB
Packet length (bytes)
Unique OP code
Packet payload (0 to 30 bytes)
Packet header